Polymer scale which builds up on the walls of reactors during polymerization causes a problem for polymer manufacturers. Polymer scale deposited on the various surfaces within the polymerization reactor causes a decrease in polymer yield and a reduction in the cooling capacity of the polymerization reactor. Further, the polymer scale deposited on the surfaces tends to come off and enters into the polymer product, resulting in production of a polymer product of lower quality. Furthermore, the removal of scale from the inner surfaces after each polymerization run requires large amounts of labor and time, resulting in the reduction of productivity. Additionally, inhalation of volatile monomers, especially vinyl chloride during the scale-removing operation causes serious health problems.
To solve such problems, a number of methods have been proposed to prevent polymer scale deposition, specifically in the suspension polymerization of vinyl chloride or a monomer mixture composed mainly of vinyl chloride. In some methods ingredients are added during the polymerization reaction itself. In other methods the walls of the reactor are sprayed with an inert film containing scale preventing agents, such as dyes or condensation polymer. These prior art methods have, in fact, been successful in some cases for the commercial production of polyvinylchloride (PVC) resin. But certain disadvantages still exist.
The present invention is an electrochemical method. The well-known compound, phenol and its alkyl derivatives are weak acids with pK values of about 10 (in water). The electrochemical oxidation of these phenol compounds produces thermoplastic polymers of high molecular weight having linear or cross-linked structures, especially where the procedure is carried out in a non-aqueous system. In the present invention phenol, its halo and/or alkyl derivatives are electrolyzed using a non-aqueous solvent and a Lewis Base. The polymer which is formed is filtered and dissolved in an alkali solvent. Thereafter the alkali solution can be diluted with water and applied to the inner surfaces of a polymerization vessel. This coating prevents the deposit of scale on the surfaces. The coating being substantially pinhole-free also prevents pass through of monomers to the inner surfaces of the reactor during polymerization.